The present invention relates to the spread spectrum communication system, and especially to the the spread spectrum communication system wherein the offset voltage pattern of frequency hopping is applied to the VCO of the PLL in the receiver thereof.
A plurality of synthesizer outputs are combined together with the carrier signal in the conventional spread spectrum communication system realized by frequency hopping, and thus a plurality of discontinuous points have occurred in the carrier phase domain. No receiver employing the coherent detection system is suitable for the spread spectrum communication system realized by frequency hopping and, especially in case that the receiver can operate for high speed data transmission, this type of receiver cannot be used for the spread spectrum communication system realized by frequency hopping.
A receiver employing an incoherent detection system has a circuit configuration complicated. Spans between adjacent carriers in the frequency domain are not arbitrary and anti-interference performance obtained by incoherent detection is normally inferior to that obtained by coherent detection.
The objective of the present invention is to present means to make it possible for the spread spectrum communication system realized by frequency hopping to perform coherent detection with a simple detection circuit so that performance of the receiver realized by employing the coherent detection system is superior than that realized by employing the incoherent detection system.